Electronic devices and systems include various electronic components that generate heat during operation, such as, but not limited to, logic processors, graphics processors, signal processing units, batteries, power supplies, display devices, light emitting components, electromechanical components, sensors, amplifiers, digital to analog converters (DACs), analog to digital converters (DACs), radio frequency (RF) transmitters, RF receivers, and system on a chip (SoC) components. It is advantageous to maintain electronic components at lower temperatures, as operating temperature is a significant factor in determining reliability and failure rates. Also, hotter components may degrade over their lifespan, and additional power may be required to compensate for the degradation, which in turn can result in additional charge/discharge cycles for a battery supplying such power. Further, higher temperatures can reduce efficiency or performance; for example, some components may exhibit leakage power dependent on component temperature. Other components may be similarly affected if heat generated by a component is not effectively removed or managed.
Decreases in component and device sizes have increased challenges for thermal management. Miniaturization of electronic components has led to increases in heat flux, with some microprocessors reaching 200 W/cm2. Also, decreases in form factor sizes for electronic devices have led to increasing compact and/or stacked arrangements that increase densities of heat generating components and restrict avenues for heat rejection. Further challenges and constraints are imposed on mobile and wearable electronic devices, as air blowers are often undesirable or impractical in such devices, surfaces that come into contact with users need to be maintained at safe or comfortable temperatures, and surfaces with low thermal resistances, such as a metal exterior surface, can still end up conducting too much heat energy to a user's body even at lower temperatures.
Various techniques have been employed for removing heat from electronic devices, including, for example, heat spreaders, heat pipes, and finned heat sinks, sometimes in combination with air flow from a passive vent or assisted by air blowers. Heat pipes and vapor chambers offer very high thermal conductivities, but their use in portable electronic devices has generally been limited to high heat flux components such as microprocessors and graphics processing units (GPUs). There remain significant areas for new and improved ideas for applying heat pipes and vapor chambers in portable electronic devices, and such improvements are also of benefit for other uses of heat pipes and vapor chambers.